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In freshwater fish, aluminum is a well-recognized gill toxicant, although responses are influenced by pH. Aluminum nanomaterials are being used in diverse applications that are likely to lead to environmental release and exposure. However, it is unclear if the effects of nanoparticulate aluminum are similar to those of other forms of aluminum or require special consideration. To examine the acute toxicological effects of exposure to aluminum nanoparticle (Al-NP)s, adult female zebrafish were exposed to either Al-NPs or aluminum chloride for up to 48 hours in moderately hard fresh water. Al-NPs introduced into test water rapidly aggregated and up to 80% sedimented from the water column during exposures. No mortality was caused by concentrations of Al-NP up to 12.5 mg/L. After exposure, tissue concentrations of aluminum, effects on gill morphology, Na+, K+ -ATPase (NKA) activity, and global gene expression patterns were examined. Exposure to both aluminum chloride and nanoparticulate aluminum resulted in a concentration dependent decrease in sodium potassium ATPase activity, although Al-NP exposure did not alter gill morphology as measured by filament widths. Decreased ATPase activity coincided with decreases in filamental NKA staining and mucous cell counts. Analysis of gill transcriptional responses demonstrated that exposure to 5 mg/L Al-NP only resulted in significant changes in expression of two genes, whereas aluminum chloride exposure significantly affected the expression of 105 genes. Taken together, these results indicate that nanoparticulate aluminum has little acute toxicity for zebrafish in moderately hard freshwater. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010. [ABSTRACT FROM AUTHOR]

Background: One of the challenges to using some flavor chemicals in aerosol products is the lack of route of administration specific toxicology data., Methods: Flavor chemicals (88) were divided into four different flavor mixtures based upon chemical compatibility and evaluated in 2-week dose-range-finding and subsequent 90-day nose-only rodent inhalation studies (OECD 413 and GLP compliant). Sprague-Dawley rats were exposed to vehicle control or one of three increasing concentrations of each flavor mixture., Results: In the dose-range-range-finding studies, exposure to flavor mixture four resulted in adverse nasal histopathology in female rats at the high dose, resulting in this flavor mixture not being evaluated in a 90-day study. In the 90-day studies daily exposures to the three flavor mixtures did not induce biologically meaningful adverse effects (food consumption, body weights, respiratory physiology, serum chemistry, hematology, coagulation, urinalysis, bronchoalveolar lavage fluid analysis and terminal organ weights). All histopathology findings were observed in both vehicle control and flavor mixture exposed animals, with similar incidences and/or severities, and therefore were not considered flavor mixture related., Conclusion: Based on the absence of adverse effects, the no-observed-adverse-effect concentration for each 90-day inhalation study was the highest dose tested, 2.5 mg/L of the aerosolized high dose of the three flavor mixtures., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: All authors are employees of Juul Labs, Inc. or the contract research organization that was compensated for performing the work.